Males and females are created with internal sensors (pheromones) that pick up vibes from the opposite sex. This is the reason why I don't feel threatened/excited when a 6 foot tall woman walks into a room as I do when a 6 foot tall man walks into the same room. Dressing up that same 6 foot tall man in a dress, makeup, and calling him Barb isn't going to tell my pheromones that he is a woman. The reason we women have these sensors is not only to help us choose a mate, but also to alarm us when there is a threat. When men approach us, our sensors kick in. We either feel safe or threatened. Even if a transwoman was very gentle and passive, our sensors are going to tell us that something isn't right.
There was a study (which I can't find now to cite) that showed women could recognize a transgender quicker than a man. Our intuition is stronger and we're able to read non-verbal cues better than men. Again, this is all part of the tools to help us approve a mate. Putting transwomen in the same private spaces as women do not make us feel safe, unless we really know the person.
I have a transgender friend who is very soft and passive. She is also small in stature. However, even I feel awkward at times and not because she is dressed like a woman. I could care less how people want to appear on the exterior. It's this uncomfortable vibe that I get because my sensors are saying that something is off.
